Many patients with inappropriate or uncertain indications had important coronary disease.

Action Points

Roughly a third of patients with diagnostic angiography deemed "inappropriate" under current appropriate use criteria had obstructive coronary artery disease, and more than 40% with "appropriate" angiograms did not.

Note that the findings raise concerns that the joint 2012 AUC guidelines for diagnostic catheterization will not be as reliable as experts had hoped for guiding decisions about who should and should not receive diagnostic angiograms.

Roughly a third of patients with diagnostic angiography deemed "inappropriate" under current appropriate use criteria (AUC) actually had obstructive coronary artery disease, and more than 40% with "appropriate" angiograms did not, according to a population-based study.

An analysis of outcomes from close to 50,000 procedures in a Canadian registry revealed that among the roughly one in 10 patients with angiography deemed inappropriate, 30.9% had obstructive coronary artery disease (CAD) and 18.9% underwent revascularization, reported Harindra Wijeysundera, MD, PhD, and colleagues of Sunnybrook Health Science Center in Ontario, Canada.

In addition, among patients with angiography deemed appropriate, 52.9% had obstructive CAD and 40% underwent revascularization. In patients with uncertain indications, 36.7% had obstructive CAD and 25.9% had revascularization, they wrote in the Annals of Internal Medicine.

The findings raise concerns that the joint 2012 AUC guidelines for diagnostic catheterization will not be as reliable as experts had hoped for guiding decisions about who should and should not receive diagnostic angiograms, Wijeysundera's group stated.

They also make a strong case against using the AUC as a tool to determine remuneration for physicians and hospitals that perform diagnostic catheterizations, he said.

"Our study would suggest that it is insufficient to do that," Wijeysundera told MedPage Today. "The scenario where funding would be withheld for procedures considered inappropriate under this measure would inappropriately punish doctors and hospitals in many cases. Clinical medicine is complex."

Diagnostic catheterization is widely used, but there is a large regional variation in its application and some believe that far too many unnecessary procedures are done, the researchers wrote.

"The implicit rationale for a procedure being defined as appropriate is that its anticipated benefit outweighs its potential harm," the researchers wrote. "However, there is a paucity of empirical evidence validating this conceptual framework."

In a 2012 study, the authors examined the AUC for revascularization and found that revascularization of patients with indications that were considered appropriate reduced death rates.

The current study was conducted to examine the validity of the AUC for predicting obstructive CAD in patients undergoing elective coronary angiography.

The study included 48,336 patients enrolled in the Cardiac Care Network of Ontario registry. The latter included all patients with suspected stable CAD who had elective angiograms at 19 hospitals October 2008 to October 2011. The patients did not have a prior coronary revascularization or myocardial infarction.

Among the study cohort, 58.2% of the angiographic studies were categorized as appropriate while 10.8% were deemed inappropriate, and 31% were uncertain, the researchers wrote. Almost half (45.5%) of the total cohort had obstructive CAD.

"Although more patients with appropriate indications had obstructive CAD and underwent revascularization (P<0.001), a substantial proportion of those with inappropriate or uncertain indications had important coronary disease," the researchers wrote.

The findings do not mean the appropriate use criteria for coronary angioplasty has no value, Wijeysundera said.

"It is certainly useful, but I think our study highlights its limitations," he said. "The AUC was very thoughtfully designed and our paper is not meant to imply otherwise. But it does not capture all of the complexities and subtleties of clinical care."

The findings also suggest that the AUC for diagnostic catheterization may need to be further refined in an effort to better achieve this goal, he added.

"Our hope is that these findings will prompt deeper thought into the next step in the evolution of this AUC," he said.

The study had some limitations.

The cohort included only patients who received angiography, so the authors could not fully validate the AUC or comment on the appropriateness scores of those who did not undergo angiography. The authors also assumed that all symptomatic patients had typical angina, and data were not available on whether symptoms were atypical.

In an accompanying editorial, Jacob A. Doll, MD, and Manesh R. Patel, MD, of Duke University Medical Center, Durham, N.C., wrote that the study shows both the "opportunities and challenges" of applying an AUC to large data sets.

They noted that the ACC Foundation and others are in the process of developing clinical decision support to help facilitate the use of AUC in clinical practice, but they also noted that use of the practice guidelines as a quality measure for public reporting and financial incentives would be problematic.

"Some variables not represented in the AUC (such as extremes of age, comorbid conditions, and patient preference) may influence decision making, and further work is needed to understand how to identify outliers," they wrote. "Professional societies, regulators and payers will need to standardize definitions so that AUC and performance measures can be applied uniformly and fairly."

They concluded that while there is interest in "systems that use big data to assess appropriateness in order to reduce costs," this is a one-sided approach to AUC.

"An ideal system would be evidence-based, use uniform and comprehensive clinical data, provide point-of-care decision support and aim to improve quality by reducing overuse and underuse," they wrote. "The AUC could be the backbone of such a system and, if trusted by all stakeholders, could provide a practice-level alternative to pre-authorization requirements or indiscriminate reductions in reimbursement."

Wijeysundera disclosed support from a Distinguished Clinician Scientist Award from the Heart and Stroke Foundation of Canada. One co-author disclosed support from a Phase 2 Clinician Scientist Award from the Ontario Provincial Office of the Heart and Stroke Foundation.

Wijeysundera and co-authors disclosed no relevant relationships with industry.

Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner

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